In collaboration with the department of transfusion medicine at the NIH, twenty donors were identified who had indeterminate Western blots for HIV-1. These donors, and controls with negative Western blots, were restudied at several time points including EIA, Western blot and PCR for HIV genetic sequences. Also, nineteen recipients of units from these donors were similarly studied. Although Western blot indeterminacy tended to persist, no evidence was found for HIV infection in any of the donors or the recipients. These data confirm the findings of other investigators that persistent indeterminacy of the Western blot in the face of a negative EIA is not suggestive of HIV infection.